First-ever transgender hate crime prosecution in US

In 2009, the US Congress expanded a federal hate crime law to include crimes motivated by a victim's sexual orientation (Getty)

A gang member was sentenced to 49 years in prison on Monday for the murder of a transgender teen, in the first-ever transgender hate crime prosecution in the United States.

Joshua Vallum pleaded guilty last December to the 2015 murder of his former romantic partner, 17-year-old Mercedes Williamson, because she was transgender.

The 29-year-old man appeared in a Mississippi courthouse before a federal judge who could have imposed a maximum sentence of life without parole.

Harper Jean Tobin, spokeswoman for the National Center for Transgender Equality (NCTE), a Washington DC advocacy group, said the murder was part of an "epidemic of violence against transgender people" in the United States.

"It's essential that biased crime against trans people be recognised as a serious national problem," she said in a phone interview.

In 2009, the US Congress expanded a federal hate crime law to include crimes motivated by a victim's sexual orientation among other factors.

Vallum, a member of the Latin Kings street gang, believed to the largest Hispanic gang in the United States, secretly dated Ms Williamson during the summer of 2014, according to prosecutors.

He decided to kill Ms Williamson, fearing that he could face retribution from other gang members if word spread she was a transgender woman, prosecutors said.

After luring his former lover to his father's home, Vallum shocked Ms Williamson with a stun gun before stabbing her repeatedly with a pocket knife.

He struck deadly blows to Ms Williamson's head with a hammer after she tried running away, prosecutors said.

This was the first case where a victim had been targeted because of gender identity that had been prosecuted under the US federal hate crime law.

"Today's sentencing reflects the importance of holding individuals accountable when they commit violent acts against transgender individuals," said Attorney General Jeff Sessions in a statement.

Vallum had previously been sentenced to life in prison in a state court for the same murder.

But federal prosecutors brought an additional lawsuit for hate crime because Mississippi lacks a statute protecting people against hate crimes based on their gender identity, the Department of Justice said.